Carbon blacks are generally produced in a furnace-type reactor by pyrolyzing a hydrocarbon feedstock with hot combustion gases to produce combustion products containing particulate carbon black.
Carbon blacks may be utilized as pigments, fillers and/or reinforcing agents in polymer compositions. As used herein "polymer" refers to a natural rubber, a synthetic rubber, an elastomer, a plastomer and/or blends or mixtures thereof.
Carbon blacks may also be utilized to impart electrical conductivity and protection from ultraviolet (UV) degradation to polymer compositions. For example, carbon blacks are widely used to minimize the degradation of polymer compositions upon exposure to UV radiation. Such UV radiation occurs as a component of natural sunlight. It is generally recognized that the degree of protection from UV degradation is improved upon use of carbon blacks having a reduced particle size, for example no greater than 25 nanometers (nm.). There is generally believed to be additional benefits from the use of carbon blacks having particle sizes no greater than 20 nm.
Carbon blacks are incorporated into the polymer composition through a variety of mixing techniques. For carbon blacks which have acceptable characteristics relating to UV protection, it is generally desirable to utilize those carbon blacks which will provide as low a viscosity as possible, and thus improve the processability of the carbon black-polymer composition mixture. Another desirable feature of carbon blacks used in such applications would be to maximize, to the extent practicable, the relative content of carbon black in the carbon black-polymer composition mixture. In order to minimize the tendency of a plastic composition to absorb moisture, it is desirable to utilize carbon blacks which possess as low a compound moisture absorption (CMA) as possible. The CMA is indicative of the moisture absorption capability of the carbon black after it has been compounded into the polymer composition of interest.
Accordingly, it would be advantageous to produce novel carbon blacks which impart improved viscosity or processability characteristics to polymer compositions into which the carbon blacks are incorporated.
It would also be advantageous to produce novel carbon blacks which impart lower compound moisture absorption characteristics to polymer compositions into which the carbon blacks are incorporated.
Further, it would be advantageous to have novel polymer compositions which have improved viscosity and/or processability characteristics, and lower compound moisture absorption.
These and other advantages are achieved by the carbon blacks and polymer compositions of the present invention.